#include <iostream>
#include <string>
using namespace std;
class Person {
  friend ostream& operator<<(ostream& out, const Person& p); 
public:
  Person(string name = "tom", size_t age = 20, string sex = "man")
    :_name(name)
    ,_age(age)
    ,_sex(sex)
    {}
  ~Person(){}

  
private:
  string _name;
  size_t _age;
  string _sex;

};

ostream& operator<<(ostream& out, const Person& p) {
  out << p._name << endl;
  return out;
}

int main()
{
  Person p;
  Person p1("jack");
  cout << p << p1;
  return 0;
}
